Instrument for plotting gear-teeth.



PATENTED NOV. 29,1904.

0. P. MOON. INSTRUMENT FOR PLOTTING GEAR TEETH.

APPLICATION FILED MAY 4. 1904.

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A TTOHNE Y8 No 776,340. PATENTED NOV. 29, 1904. C. F. MOON.

INSTRUMENT FOR PLOTTING GEAR TBETI-L.

APPLICATION FILED my 4. 1904.

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WIN/58855.49 I 5 INVEN r00 C'YaarnJZ/ifama \Mf Z6; By /M Q A TTOHNE Y8NlED STATES Patented November 29, 1904.

CLABORN F. MOON, OF GREENSBORO, NORTH CAROLINA, ASSIGNOR TO HIMSELF ANDTHOMAS J. MoADOO, OF GREENSBORO, NORTH CAROLINA.

INSTRUMENT FO R PLOTTING GEAR-TEETH.

SPECIFICATION forming part of Letters Patent No. 776,340, dated November29,1904.

Application filed May 4, 19.04. $erial No. 206,352. (No model.)

drawings, forming a part of this specification, 1n Wl11Cl1 similarcharacters of reference indicate corresponding parts in all the figures.

Figure l is a side elevation showing my invention ready for use. Fig. 2is a plan view of the same, certain working parts beingexposed to view.Fig. 3 is an enlarged fragmentary vertical section upon the line 3 3 ofFig. 2 looking in the direction of the arrow. Fig. 4 is an enlargedelevation of the indexdisk. Fig. 5 represents both a plan and a sideelevation of the arm carrying the toothform. Fig. 6 is a perspectiveview of the lid or cover 28; and Fig. 7 is a section upon the line 7 7of Fig. 3, showing a diiferent typeof arm for carrying the tooth-form.

A bracket 8 is provided with holes 9, whereby it may be mounted upon awall, and is further provided with a clamp 10 and shoulder 11, wherebyit may be secured upon a drawing board or table 12. This board may alsofurther be provided with lugs 13 for the purpose of engaging a flatsurface, thus giving the board additional support. A pin 14 is rigidlyconnected with the bracket 8, and pivotally mounted upon this pin is ajournalyoke 15, provided with a sleeve 16, carrying a rod-section 17.This rod-section is provided with a flattened clamping member 18, whichis engaged by a similar member 19, carried upon a rod-section 20. Bymeans of a screw 21 the two clamping members may be gripped together astightly as may be desired, so that the rod-sections 17 20 may be placedat any desired angle relatively to each other and more particularly inFigs. 1 and 2.

when secured rigidly in this relative position will yet be free to swingupon the pin 14. The rod-section 20 carries a vertically-disposed sleeve21, preferably integral therewith. A head 22 is provided with a sleeve23, which fits loosely into the sleeve 21*, but may be secured tightlyin position with relation to the sleeve 21 by means of a thumb-screw 24.

By tightening or loosening this thumb-screw the head 22 may be turned toany desired angle. A central spindle 25 passes loosely through thesleeve 23 and is revoluble therein. A worm-gear 26 is keyed rigidly uponthe spindle 25 and is engaged by a worm 27, as shown A cover 28 isprovided with fastening members 29, whereby it is secured upon the head22 for the purpose of protecting the working parts from dust. The worm27 is mounted upon a spindle 30, this spindle being provided with aflattened portion 31, which engages a slot 32 in a crank-arm 34. Thiscrank-arm is provided with a spring-plunger 35, controllable by a handle36, whereby the plunger may be tomporarily withdrawn a short distance inthe direction in which the handle 36 is pulled. An index-disk 37 isprovided with notches 38,

disposed oppositely in the edge thereof and adapted to engage a lug 39,rigidly connected with the head 22. but may be taken off and itsposition reversed, so that the spectator may behold either of its twoflat faces, as desired. This disk is provided upon each of its faceswith a large number of circles 39, 40, and 41, and each circle isprovided with a series of holes 42, 43, and 44. Preferably all of thecircles having an even number of holes are disposed upon one face of thedisk and circles having an odd number of holes upon the opposite facethereof. The disposition of the holes and the circles is preferably suchthat the upper portion of the disk presents a row of holes disposedradially, as shown in Fig. 4. By pulling the handle 36 slightly outwardor to the left, as will be seen in Fig. 3, the spring-plunger may bewithdrawn from any hole it may chance to occupy in the disk The disk 37is stationary,

this action.

37, and upon being thus detached the crankarm may be rotated within anydesired limits relative to the disk 37 and secured in position byallowing the spring-plunger 35 to enter any desired hole. The crank-arm34 being fitted slidably upon the flattened portion 31 of the spindle30, the spring-plunger may be moved toward or from the center of theindexdisk, and thus brought to any desired circle. The gearing of theworm 27 and of the wormwheel 26 is such that forty turns of the crankarm34 correspond to oneturn of the wormwheel 26 and spindle 25.

Mounted upon the lower end of the spindle 25 is a ring 45, securedthereto by means of athumb-screw 46. An arm 47 passes tangentiallythrough a slot in the spindle 25 and through an opening in the ring 45,as indicated in Fig. 1. This arm is provided at its outer or free endwith a slot 48, whereby it is bifurcated, as shown in Fig. 5. Atoothform 49 is integrally mounted upon a plate 50, which engages theouter or free end of the arm 47, the latter being recessed for thepurpose. The plate 50 is sprung into position, so as to support thetooth-form, as indicated in Fig. 5, the slot 48 permitting The arm 47and the tooth-form 49 are of the kind used for cutting so-calledexternal gear-teeth. For cutting internal gear-teeth, however, I preferto use the type of device shown in Fig. 7. In this view the tooth-form51 is mounted upon an L-shaped arm 52, which fits into a sleeve 53,integrally mounted upon a rod 54, this rod being adjustablelongitudinally in relation to the ring 45, as shown more particularly inFig. 7. In other Words, I merely pull out the arm 47 and insert insteadthe comparatively short rod or arm 54. It will be noted that the arms 47and 52 are so arranged that the center of the tooth-forms 49 or 51 isexactly in line with the center of the spindle 25, as will be seen byinspecting Figs. 2 and 7.

My invention is used as follows: The board 12 being arranged as shown inFig. 1, the spindle 25 is mounted at a point representing the center ofthe wheel, the teeth of which are to be plotted. If this wheel is to beprovided with externally-disposed teeth, the arm 47 is inserted throughthe ring 45 and spindle 25 and so adjusted as to give the wheel thedesired radius. The proper tooth-form 49 now being placed in position,the device is ready for use. Each time the spring-plunger 35 is insertedin a hole the tooth-form 49 is necessarily secured in proper position toserve as a templet for tracing the tooth. The operator merely runs hispencil around the toothform, following its contour and marking itscorrect position upon the paper used for plotting. If now one turn ofthe crank-arm 34 represents one-fortieth of the turn of the arm 47 or52, it follows, of course, that if the gear is to be provided with fortyteeth the crank is turned forty times and the spring-plunger is broughtaround to the same hole forty times, so that the tooth is moved step bystep around a circle representing the circumference of the wheel to beplotted. If, however, the wheel to be made is to have any other numberof teeth-such, for instance, as thirty-nine the crank-arm is movedaround, as above described, but is carried a little beyond thestarting-point, and the spring-plunger is inserted in the nextconsecutive hole when cooperating with the circle having thirty-nineholes. For instance, if, as is usually done, the operator begins hisreckoning from a predetermined hole in the upper portion of the disk, heturns the crank around, say, to the right, a little more than onecomplete revolution until the plunger comes opposite the nextconsecutive hole to the right of the one selected, thus moving thetemplet an angular distance representing the distance between twoconsecutive teeth to be formed. Thetooth is now indicated by running apencil around the templet or tooth-form and the crank-arm moved aroundagain a little more than a complete revolution, stopping at the nextconsecutive hole a little farther to the right from the startingpoint,and so on until the entire series is completed. It follows, therefore,that the teeth must be spaced equidistant and that the tooth-form isheld rigidly in position and with mathametical accuracy. By selectingthe appropriate circle having the proper number of holes almost anyconceivable variation can be made in the number of teeth to be plottedfor a wheel. For instance, as the inner circle 39 contains eighteenholes it is obvious that if the plunger be stopped at a point one, two,or three holes removed from the starting-point and after completing therevolution the teeth will be spaced farther apart than if the outercircle 41, containing seventytwo teeth, be selected and the instrumentmanipulated in the same manner. If desired, the plunger can be movedaround, as above described, and stopped at distances representing two,three, or any desired number of holes removed from the starting-pointand from each other.

This instrument admits of general use, but is of peculiar value toarchitects, engineers, draftsmen, pattern-makers, and all other personswho may from any cause desire to divide circles or portions thereof intoportions separated by radially-disposed lines. It admits, therefore, ofquite a variety of uses. Its simplicity is such that it can be operatedby any person of ordinary intelligence.

The spacing-head may be used for supporting a lamp or holding drawinginstruments, which may rest upon the flat upper surface of the cover 28.

Having thus described my invention, I claim as new and desire to secureby Letters Patent 1. In an instrument for plotting gear-teeth,

IIO

the combination of a revoluble spindle, means for securing the same inpredetermined definite positions, a comparatively short rod connectedwith said spindle and provided with a sleeve, and an L-shaped armengaging said sleeve and having a tooth form mounted therein.

2. In an instrument for plotting gear-teeth, the combination of ajointed rod provided with a head, gearing supported by said head, meanscontrollable at will for actuating said gearing, mechanism forindicating the amount of actuation thereof, means connected with saidlast-mentioned mechanism and adapted to be moved into different angularpositions, said means supporting a movable to0th-form, and means forsupporting said jointed rod.

3. In an instrument for plotting gear-teeth,

the combination of a member admitting of angular movement into differentpositions relatively to a common center, a head. mounted upon saidmember and provided with a fiat upper surface capable of use as asupport for a lamp, a templet, and mechanism connected with said headfor actuating said templet.

4. In an instrument for plotting gear-teeth, the combination of a diskhaving oppositelydisposed faces provided with holes, said diskbeing-reversible so as to present either of said faces toward theoperator, a manuallyoperated member movable angularly with reference tosaid disk and provided with mechanism for engaging said holes, gearmembers connected with said manually-operated member and controllablethereby, an arm connected with one of said gear members and adapted tomove angularly into dificrent positions, and a tooth-form mountedupon'the outer or free end of said radially-disposed arm.

5. In an instrument for plotting gear-teeth, the combination of ajointed rod provided with a head, means for temporarily securing saidhead in a predetermined fixed position, gearing supported by said head,means for actuating said gearing, mechanism for indicating the amount ofactuation thereof, and means for revolubly supporting a movabletoothform, said means being controlled by said gearing.

6. The combination of a disk having oppositely-disposed faces providedwith holes, said disk being reversible so as to present either of saidfaces toward the operator, a manually-operated member movable angularlyin relation to said disk and provided with mechanism for engaging saidholes in either of said faces according to the position of said disk,gearing connected with said manuallyoperated member and actuatedthereby, and a templet controllable by said gearing for the purpose ofdisclosing the position of a tooth to be formed.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

OLABORN F. MOON.

WVitnesses:

J NO. K. MOILHENNY, Jr., HARRY N. LA'IHAM.

